How do i remove objects within another object's collection?
The 'connector' object is not actually a collection. Most probably, the other four objects are parented to the connector object, thus causing them to be shown under this object in the Outliner.
In response to your second question, the objects are actually getting moved to the Scene Collection, but they remain where they are greyed out simply to display the hierarchy (as they are still parented to the 'connector' object). Scrolling down to the bottom of the Outliner should find the four objects in the Scene  Collection.
An alternative way to move these objects is to press M.